• 文献标题:   Correlated states in magic angle twisted bilayer graphene under the optical conductivity scrutiny
  • 文献类型:   Article
  • 作  者:   CALDERON MJ, BASCONES E
  • 作者关键词:  
  • 出版物名称:   NPJ QUANTUM MATERIALS
  • ISSN:  
  • 通讯作者地址:   CSIC
  • 被引频次:   2
  • DOI:   10.1038/s41535-020-00258-6
  • 出版年:   2020

▎ 摘  要

Moire systems displaying flat bands have emerged as novel platforms to study correlated electron phenomena. Insulating and superconducting states appear upon doping magic angle twisted bilayer graphene (TBG), and there is evidence of correlation induced effects at the charge neutrality point (CNP) which could originate from spontaneous symmetry breaking. Our theoretical calculations show how optical conductivity measurements can distinguish different symmetry breaking states, and reveal the nature of the correlated states. In the specific case of nematic order, which breaks the discrete rotational symmetry of the lattice, we find that the Dirac cones are displaced, not only in momentum space but also in energy, inducing finite Drude weight at the CNP. We also show that the sign of the Drude weight anisotropy induced by a nematic order depends on the degree of lattice relaxation, the doping and the nature of the symmetry breaking.